Patent GB-911193-A (GB)
Title: Improvements in or relating to control arrangements in automatic telephone systems
Inventor: ALLUM ROBIN DEVENISH
IPC: H04M15/06
Filed: 1960-06-06
Abstract: 911,193. Automatic - exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd., and STANDARD TELEPHONES & CABLES Ltd. June 9, 1961 [July 6. 1960], No. 23600/60. Class 40 (4). Accumulated subscribers' meter totals are recorded on a magnetic drum at each exchange of a system in which a central accounting station may extract the total accumulated for any particular subscriber by transmitting to the subscriber's exchange under the control of punched tape the subscriber's address in response to which the total is read out and sent back to the central station to operate a printer, transmission between the station and exchanges being in telegraph code. At an exchange a magnetic drum provides library tracks on which subscribers are identified and associated meter tracks on which meter totals are recorded. Should p.b.x. junction groups, or party lines be involved an auxiliary library track is employed to record sequence numbers, group numbers, or Y-party numbers. The telegraph code employed is the Elliott code comprising six 20-millisecond intervals, for mark or space signals conveying a start signal and a five-element code, and a 30-millisecond interval conveying a finish signal. An operator at the central station may connect a tape reader and teleprinter (see Fig. 7), to an outgoing and incoming trunk, respectively, to a wanted exchange. The tape reader controls a relay set, Fig. 9 (not shown), to transmit the code. In demand of a meter total the tape reader transmits a setting up signal followed by the directory number of the wanted subscriber, or the group and sequence number of a party line or p.b.x. line, followed by a transmission finished code. At the wanted exchange a bit-timing circuit supervises an incoming digit store and a digit distributer to set up the received address on sets of bi-stable circuits in a control equipment store. When an address has been transmitted the tape reader waits until the teleprinter has received the wanted meter total until it proceeds with its next address. The exchange directory or group number recorded in the control equipment store is translated to a modified binary code and the sequence number, if any, is converted to binary code to match the appearance of this data on the magnetic drum. Comparator circuits are now connected to determine the position on the drum of the wanted meter store, the search being conducted over a number of simultaneously scanned tracks. Once the position is found in terms of clock pulses it is recorded in an equipment number comparator which governs reading out of the meter track to the control equipment store. The binary code from the meter track is then translated by a meter code converter to a form suited to transmission in Elliott code under control of the bit timer and a meter code transmitter. The printer receives and records the total adjacent its record of the transmitted address and then signals the tape reader to proceed with the next address. The exchange equipment is described in the Specification by means of so-called " circuit script." Specification 801,681 is referred to.